The invention pertains to a road milling drum wherein the road milling drum, which carries a plurality of road milling bits, is a component of a road milling machine. More specifically, the invention pertains to an improved road milling drum wherein the road milling drum, which carries a plurality of road milling bits (or road planing bits) and is a component of the road milling machine, is capable of modification to adjust (or vary) its lateral cutting width.
Over time and use, a roadway becomes worn and uneven to necessitate renovation or resurfacing thereof. A typical way to resurface the roadway is by the removal of the top layer or region of roadway material (e.g., asphaltic material or concrete or the like) by the use of a road milling machine. In other words, a road milling machine mills roadway surfaces to remove a top layer or region of material prior to resurfacing.
A road milling machine comprises many components, but a major component thereof is a road milling drum. Typically, a road milling drum is a cylindrical drum that carries a plurality (e.g., sometimes hundreds) of road milling bits at the surface thereof. In this regard, U.S. Pat. No. 6,877,818 B1 to Gaertner et al. discloses a road milling drum. When in operation, the road milling machine drives the road milling bits carried by the road milling drum into the top region of the roadway to break up the top region into pieces. Many times, and especially in the case of asphaltic roadway material, a conveyor transports the pieces into a truck or the like for transport to a recycling facility.
The removal of roadway material generally must satisfy pre-determined government specifications. Oftentimes, these specifications require very specific milling widths for the removal of roadway material. Further, the milling widths for a particular job may vary at different locations throughout the job site. While the contractor could use a number of road milling machines wherein each road milling machine would address a specific cutting width, such a strategy would require an inordinately large investment in road milling machines. In addition, such a strategy would tie up a number of road milling machines on one milling job.
In order to address a situation wherein the milling widths for a particular job may vary at different locations throughout the job, contractors have used road milling drums with adjustable milling widths. In this regard, the following United States patent documents discloses road milling drums that possess the capability to adjust the milling width: U.S. Pat. No. 5,505,598 to Murray, U.S. Pat. No. 5,722,789 to Murray et al. and U.S. Pat. No. 6,213,560 to Lindblom. Even though the above-listed patents disclose adjustable width road milling drums that address a situation wherein the milling widths for a particular job site may vary at different locations throughout the job, these road milling drums have drawbacks.
In earlier adjustable-width road milling drums, one significant drawback has been that critical regions where the drum attaches to the machine are exposed to the dirt and debris inherent in a road milling operation. These critical regions contain exposed bolt heads, threaded holes, keyways, and the like that collect dirt and debris thereby rendering it more difficult to detach the drum from the machine. Such an increase in the difficulties connected with detaching the drum from the machine increases operating costs and decrease operating efficiencies for the roadway milling operation.
Earlier adjustable-width road milling drums require many drum segments in order to achieve the desired milling widths. The need to keep many drum segments on hand at the job site increases the overall expense for the roadway milling operation.
It becomes apparent that there would be an advantage to provide a road milling drum that can accommodate different milling widths. It is also apparent that there would be an advantage to provide a road milling drum that can accommodate different milling widths, and wherein the critical regions where the drum attaches to the machine are protected from exposure to the dirt and debris inherent in a road milling operation. Finally, it becomes apparent that there would be an advantage to provide a road milling drum that can accommodate different milling widths without the need to use many drum segments.